Electrohome G07 missing B+

[jehuie]

I'm trying to repair a G07. Checked fuses and they are fine. Replaced caps. Monitor is completely dead. No neck glow. No B+ reading at all. It's getting power though since it zapped me pretty good when I had it on the bench.

Anyone care to give me some ideas on where to look from here? Thanks!

 

[chris25810]

Check the white 2 ohm resistor thats sitting on the black frame side of your chassis. It's underneath the large white resistor that's mounted to the frame.

 

[jehuie]

Check the white 2 ohm resistor thats sitting on the black frame side of your chassis. It's underneath the large white resistor that's mounted to the frame.

Thanks. I had looked at that already. I'm not sure how to test the resistor. It doesn't look cracked though. And I tested it with my meter for continuity and it beeped so I'm assuming it's not open at least. Do I need to disconnect the resistor to really check it?

 

[jehuie]

Anyone else? I''m stumped!

 

[Dokert]

R902 as Chris has suggested should be tested using the ohm feature of your meter NOT continuity / diode test.

I would also test R901 as well.

 

[jehuie]

R902 as Chris has suggested should be tested using the ohm feature of your meter NOT continuity / diode test.

I would also test R901 as well.

Thanks. I was assuming (wrongly apparently) that since I was getting continuity there would be at least some level of voltage getting through when I went to measure it. I'll check them out.

Any idea what the ratings should be on these? I'm looking for the manual online. It's a G07-CBO. There are a bunch of them in the following link but I don't know which would be correct since this one is listed by name.

http://arcarc.xmission.com/PDF_Monitors/

 

[jehuie]

Ok, the big resister mounted to the side is reading 0.22 ohms. Pretty sure that's not correct. Right? The R902 reads 2.3 ohms. That is, if I'm reading this correctly.

I don't see any markings on the first one so I'm still not sure what it should be rated at. R902 says it's a 7W 2"Ohm symbol"K. I have no clue how to make an ohm symbol on the keyboard. But does this mean it's rated at 2K ohms? It seems like the would put the K before the ohm symbol if that's the case.

Sorry for being such a newb about this. I haven't replaced these big resistors before that I can recall. I actually have a variety of old chassis that I thought about stealing one from but it turns out I don't have any spare G07's. I can head to Fry's Electronics once I figure out what these dudes are.

 

[DarrenF]

I have no clue how to make an ohm symbol on the keyboard. But does this mean it's rated at 2K ohms? It seems like the would put the K before the ohm symbol if that's the case.

Copy & paste this: Ω
No, it's a 2Ω 7W. Not sure what the K is there for in your case... 2K0 would be 2KΩ

Regarding the other readings... no offense, but I'm not certain you know how to operate/read your meter. Is it a manual range, or auto-ranging meter? If it's manual, you'll need to know where to put the decimal, and the implied power of 10 for the range setting, to read it properly. If it's auto, you'll need to know how to interpret its output as well (i.e. how it indicates the range; if the output is Ω, kΩ or MΩ).

 

[jehuie]

No offense taken at all. I unsoldered the resistors so that I would be sure to be measuring them properly. It's not an auto-ranging meter and the only way I could get any reading on the big one was to go to the lowest setting. Which was 200. At that setting it read 0.22. So does that mean .22 ohms? Or do I need to multiply that by something now?

 

[Dokert]

No offense taken at all. I unsoldered the resistors so that I would be sure to be measuring them properly. It's not an auto-ranging meter and the only way I could get any reading on the big one was to go to the lowest setting. Which was 200. At that setting it read 0.22. So does that mean .22 ohms? Or do I need to multiply that by something now?

that means it is bad

 

[ELutz]

The big resistor that mounts on the side is 220 ohms.....since you're getting .22 ohms......I have to ask, are you reading your meter correctly?

Also, If you're getting zapped while the monitor is on the bench......that means C904 is storing a charge and not draining. About the only thing that will keep that big filter cap from draining is a blown F901 fuse....this will also give your B+ a zero reading. Pull that fuse, I bet it's blown.

Edward

 

[jehuie]

The big resistor that mounts on the side is 220 ohms.....since you're getting .22 ohms......I have to ask, are you reading your meter correctly?

Also, If you're getting zapped while the monitor is on the bench......that means C904 is storing a charge and not draining. About the only thing that will keep that big filter cap from draining is a blown F901 fuse....this will also give your B+ a zero reading. Pull that fuse, I bet it's blown.

Edward

Thanks guys. I'll check the fuse again. I didn't pull it to check it before. I'll get a socket for the thing while I'm at it. Can someone point me in the right direction for the manual so I don't have to keep pestering you for parts info?

And hey, you guys are the best!

 

[jehuie]

Ok, I'm heading to Fry's Electronics in a bit and hope to pick up the fuses with holders and the correct resistors. I have the manual now but I'm having a dickens of a time deciphering which ones are which. Where the heck is the big one hanging on the side? How many watts is it? And R902 is listed as:

Wirewound 2R0 7W 10%

So this is 2 Ohm, 7 Watts, right?

 

[ELutz]

Ok, I'm heading to Fry's Electronics in a bit and hope to pick up the fuses with holders and the correct resistors. I have the manual now but I'm having a dickens of a time deciphering which ones are which. Where the heck is the big one hanging on the side? How many watts is it? And R902 is listed as:

Wirewound 2R0 7W 10%

So this is 2 Ohm, 7 Watts, right?

Here you go.....
http://arcarc.xmission.com/PDF_Monitors/Electrohome G07-904_Manual.pdf

The big resistor in question is R01....220 ohm 20 watt....
...and yes, 2 ohm 7 watt is correct for what you listed above.

Edward

 

[jehuie]

Here you go.....
http://arcarc.xmission.com/PDF_Monitors/Electrohome G07-904_Manual.pdf

The big resistor in question is R01....220 ohm 20 watt....
...and yes, 2 ohm 7 watt is correct for what you listed above.

Edward

Thank you again! I went to Fry's Electronics last night hoping to grab the parts but they had NONE of them. No fuse holders that can be soldered on, no fuses with the standoffs and neither of the resistors. I guess I'll be hunting online.

 

[Fudd]

i've had a couple g07 chassis where the 220ohm resistor appeared to be shorted. turned out the VR was the problem. with the wires from the resistor to the vr attached the resistor was shorted, remove all the wires from the VR and it tested correctly. replacing the vr was the solution.

this may or may not be the case in your situation.

 

[ELutz]

i've had a couple g07 chassis where the 220ohm resistor appeared to be open. turned out the VR was the problem. with the wires from the resistor to the vr attached the resistor was open, remove all the wires from the VR and it tested correctly. replacing the vr was the solution.

this may or may not be the case in your situation.

I think you want to substitute "short" for "open"

Edward

 

[Fudd]

correct and fixed

 

[jehuie]

Ok, here's the latest:

I checked fuse 901 and yep, it was blown. Replaced it. Both of the large resistors check out fine. Replaced the HOT and the Voltage Regulator. Powered it up and....nothing. Same thing, no pic, no B+ nothing.

So is it likely to be the flyback then? Any other suggestions would be welcome with open arms! Oh, is it likely that I blew the fuse again? I haven't checked it yet. Do I need to unsolder it to check it properly?

 

[gregatron]

Ok, here's the latest:

I checked fuse 901 and yep, it was blown. Replaced it. Both of the large resistors check out fine. Replaced the HOT and the Voltage Regulator. Powered it up and....nothing. Same thing, no pic, no B+ nothing.

So is it likely to be the flyback then? Any other suggestions would be welcome with open arms! Oh, is it likely that I blew the fuse again? I haven't checked it yet. Do I need to unsolder it to check it properly?

If you blew the fuse then yes, most likely the fly is bad. If you didn't (although I'm betting you did) you have an open circuit or cracked trace in the main power circuit.